Partners
by encantadaa
Summary: AU set season 1. After closing a tough case similar to that of her mother's, Kate disappears from the precinct. A concerned Castle tracks her down at a bar. He drops the playboy, immature, self-centered persona and shows her the real Castle. The one who is willing to do anything for the people he cares about. **Co-authored with thebazilelord**


_**This story was co-authored with thebazilelord**_

* * *

"Mr. Mason, you are under arrest for the murder of Jamie Wilks."

Her tone is business-like, but judging by the rigid set of Beckett's shoulders and the flashes of panic in her eyes, she is anything but calm. As she locks the handcuffs around the suspect's wrists, she keeps her eyes carefully trained on the ground, refusing to meet Castle's gaze.

Something is obviously wrong; in fact, she's been acting strange since the moment they crossed the tape at the crime scene and spotted the victim's body crumpled against the wall in a Manhattan alleyway, the deep crimson blood seeping from the single stab wound in her chest. Castle has never seen his partner so flustered over a case.

Looking at her now, it is clear that she wants to be anywhere but in this room.

Beckett leads Mr. Mason out of the interrogation room and passes him to Esposito, barking out a short list of orders to the detective. She doesn't even wait for a response from Esposito before she darts into the bullpen, grabs her jacket from the back of her desk chair, and bolts to the stairwell.

"Beckett," Castle shouts, voice laced with worry. But she ignores him, rounding the corner and disappearing down the stairs. Dumbfounded, he stands frozen in place for a moment, staring at the now-empty space.. Finally, he snaps out of his daze, bounding down the stairs after his fleeing partner. He's only worked with Beckett for a little over two months, and doesn't know her well enough to know where she might go, but he isn't about to let her get away.

Castle pushes past people in the lobby, finally throwing the building's front door open and dashing out to the sidewalk. He frantically looks around, scanning the faces in the midafternoon crowd. Just when he thinks he's lost her, he spots the back of her head, her retreating form quickly disappearing into the crowd.

"Excuse me," he murmurs as he squeezes through a group of noisy tourists, half-jogging down the sidewalk until he finally gains some ground on Beckett. He follows her from a reasonable distance, keeping his eyes carefully trained on the back of her head. Finally, she darts into a small, rundown building, and he ducks inside after her, not even bothering to look at the place he's entering.

It takes a moment for his eyes to adjust to the dim light in the room, but when they do, he's able to discern shelves against the wall lined with bottles of all sizes, and the hard oak of a bar counter. The metal stools are all vacant- all vacant, that is, except for the one in the far corner. The bar's single occupant is hunched in her seat, her head in her hands.

Castle strides toward her, pulling out the stool beside her and plopping himself into it confidently.

"Two glasses of scotch, on the rocks," he calls to the bartender with a nod.

Beckett's head jerks up, and she turns to Castle, a look of surprise on her face.

"Unless you want something different," he shrugs, quirking an eyebrow.

Her shock quickly morphs into a glare as she tilts her head back in frustration. "Castle, what are you doing here?" she murmurs, her jaw clenched in aggravation.

"Well, I was just strolling through the neighborhood, and I thought to myself, 'Wow, I could really use a drink right now.' And I found this _wonderful_ , high-class bar, and thought it looked like the perfect place," he says with a smirk. "What a coincidence that you're here, too!"

She huffs, but doesn't respond as the bartender slides their drinks to them. She seems to battle with herself as she stares at the amber liquid, her jaw clenched. After a moment, she tosses the drink back in a single gulp.

Castle fights the urge to make a flippant remark, choosing instead to wait for her to speak. After a moment, she takes a deep, shaky breath.

"I was nineteen," she starts, her voice quiet. He looks up at her, his eyebrows raised in askance.

"Dad and I were supposed to meet my mom for dinner one night, but she never showed. When we got home, we found a detective waiting at the door for us. They'd found my mom's body."

Castle's breath hitches, catching in his throat. "It was just like this case," Beckett continues. "She was found in an alley just like that one, multiple stab wounds in her chest. And when I saw our victim out there yesterday, I just..."

Understanding washes over him, and he feels a deep pain and sadness for her. No wonder she'd been so on edge as they worked the case- she'd been flooded with memories of her mother's murder. He stretches a hand toward her tentatively, but stops himself before he touches her arm, simply letting his hand rest on the countertop.

If Beckett notices his gesture, she doesn't acknowledge it, taking another deep breath. "They never solved her case," she says, her voice tight with emotion. "It was attributed to random gang violence, and no one bothered to look any further into it. I tried to investigate, but I poured my whole life into it, and it almost destroyed me. It took a year of therapy before I was able to put it behind me and move on with my life. But every time I cross the tape at a crime scene, I think of that night, and my mom."

"Beckett, I'm so sorry," he breathes. "I had no idea."

"Yeah, well," she shrugs. Beckett shakes her head sadly, her shoulders slumping forward in defeat. "Sorry to unload that on you," she rasps, her voice breaking as her eyes shimmer with unshed tears.

The wounded, vulnerable woman sitting next to him barely resembles the hard-edged, quick-witted detective that he's used to seeing. Castle wants to wrap his arms around her; to cradle her against his chest and comfort her as she cries. But that is not the kind of relationship they have. He settles for laying a hand on her shoulder, squeezing it lightly in an attempt to comfort her. He hopes that he isn't crossing a line with her; that he isn't breaching the unspoken boundaries that define the parameters of their partnership.

To his surprise, she doesn't shake off his hand. Rather, her lips turn slightly upward as she reaches a hand up to swipe under her eyes.

"You're extraordinary, you know that?" Castle says quietly, and she huffs out a humorless laugh in response. "I mean it, Beckett," he adds. "You are so driven and passionate about your work, and that helps you sympathize with the victims in ways that no one else can. You don't give up. And I think that makes you amazing."

He pauses for a moment, choosing his next words carefully. "Maybe you haven't solved your mom's case yet, but that doesn't mean you never will, and it sure as hell does not make you a bad cop- it makes you better. So I just want to let you know that I'm on your side."

Castle tentatively moves his hand to rest on top of hers, and she slowly meets his eyes. He swallows hard, nervous for her reaction, as she stares at their hands, taking a deep breath to steady herself. Finally, she flips her hand underneath his, wrapping her fingers around his and squeezing lightly. Her eyes flick up to meet his again, and the gratitude shining in them leaves him breathless.

"Thank you," she whispers, so quietly that he almost doesn't hear it.

They sit in silence for a while, each lost in their own thoughts. Finally, the sharp trill of Beckett's phone causes them both to jump. She sighs as she slips her fingers out of his and pulls her phone out of her pocket, hitting the button to silence the device.

"It's the precinct." she mutters solemnly. "I'd better get back."

"We," Castle corrects softly. "We'd better get back."

She smiles at that. "Yeah. We."

They rise from their seats and head towards the door. Right before they step outside, Beckett reaches out to stop him. "Castle," she says, taking a deep breath. "Thank you for listening, and for… being there for me. You're a good guy,"

He's touched by her admission, but simply smiles in return as he holds the door open for her. "That's what partners are for."

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 _ **Author's note:**_ _This is the product of three hours spent in a coffee shop downtown with thebazilelord. We actually co-wrote this story, discussing plot details and making all decisions together. I am the one posting it officially, but please remember that I'm not the only writer! This is our first co-writing adventure, and there may be more in store for you during the coming year._

 _Thanks to Cathey (Trinity Everett) for beta-ing for us._


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